In general, higher voltage may be applied to electronic products, such as communication devices connected to telephone circuits, when surge current caused by induction lightning is applied to the electronic products or telephone lines make contact with power lines. For this reason, a fuse used in the communication device must have time lag characteristics to endure against the surge current caused by the induction lightning as well as current blocking characteristics to block current causing malfunction of the communication device.
Recently, as the size of devices has become reduced, the current blocking characteristics and the time lag characteristics are required for the surface-mount type small fuse.
The conventional small fuse includes a base, a pair of lead wires extending by passing through the base while being spaced apart from each other, a fusing element for connecting ends of the lead wires to each other, and a cover coupled with the base to receive the fusing element and the lead wires therein.
The fusing element and the lead wires are made from an alloy of copper and tin so that they have flexibility so as to be bent easily. The base and the cover are individually manufactured by using thermoplastic resin and then coupled with each other to define a space therebetween to receive the fusing element and end portions of the lead wires adjacent to the fusing element.
The small fuse is mounted on the PCB of the electronic product through the lead wires extending out of the base and the fusing element of the small fuse is melted when the over current is applied to the PCB, thereby protecting circuits of the PCB.